package com.hx.collection;

import java.util.Collection;
import java.util.HashSet;

/**
 * @author jxlgcmh
 * @create 2019-05-07 14:14
 */
public class SetDemo1 {
    public static void main(String[] args) {
        Collection set = new HashSet();
        set.add(1);
        set.add(1);
        set.add(null);
        System.out.println(set.size());
    }
}
